I. Field of the Invention
The present invention relates generally to electrical apparatus adapted to be directly coupled to non-metallic sheathed cable without the necessity of removing the sheathing and/or insulation from the wires of the cable. The present invention relates more specifically to electrical switch and/or plug receptacle apparatus which are adapted to be so coupled to the sheathed cable and which are further adapted to be secured to a wall or like structure without the necessity of a junction box or the like.
II. Description of the Prior Art
In construction of buildings such as homes, offices and the like, it is necessary to provide electrical plug receptacles (also referred to as outlets) and electrical switches (to control lights, for example) along the walls of such buildings. Conventionally, to provide electricity to the plug receptacles and/or switches, metal or plastic junction box units are mounted at various locations within the walls of the building. Cables comprised of three or more wires are then strung within the walls and between various junction boxes such that looped portions and/or one or more terminal ends of cables are positioned within each junction box. The cable is then coupled at one end to a source of supply such as at a fuse or breaker box and at the other end (or ends) to the plug receptacles, switches, lights, etc.
Typically, a non-metallic sheathed cable includes three wires. One of the wires is referred to as a hot wire and is coated with a black plastic insulation. A second wire is referred to as a neutral wire and is coated with a white plastic insulation. Finally, the third wire is referred to as a ground wire and it is not coated with insulation. The ground wire is, however, usually surrounded by paper and the hot and neutral wires are disposed on opposite sides of the ground wire and parallel thereto. In this manner, a flat cable is formed which has a width greater than its height in cross-section. The three side-by-side wires (including any insulation and paper) are then encapsulated in a plastic non-conducting sheath. Thus, to couple the cable to the power source and the apparatus (e.g., plug receptacle or switch), access must be had to the individual wires within the cables in order to connect the individual wires to the appropriate junctions at the source and at the electrical plug receptacle and/or switch apparatus.
The manner in which the wires are connected to the plug receptacle and/or switch device typically requires substantial expenditure of time and labor to accomplish. For example, it is known to provide screws about which individual wires of the cable may be received and then secured to threaded conductors attached to the housing or body of the plug receptacle or switch apparatus. These conductors are then coupled electrically to the respective plug receptacle contacts or switch poles within the housing of the apparatus.
To make the typical electrical interconnection just described, an electrician must typically make a cut in the looped portion of the cable which was strung through the junction box. This cut is usually made to sever the cable into two portions, whereby to have two terminal ends of the cable available in the junction box. Whether a loop is cut, or a terminal end of a cable is previously available at the junction box, the individual wires cannot be readily accessed until the electrician removes a portion of the sheathing material from each terminal portion of the cable. During this operation, not only is time required, the electrician must be careful not to nick any of the insulation covering either of the hot or neutral wires. Thereafter, the electrician must strip or remove some of the insulation from those wires which are to be coupled to the plug receptacle and/or switch device. Further, if the terminal end of one wire is to be coupled to the terminal end of another wire so as to complete a circuit, some of the insulation of those wires must similarly be removed and the exposed portions of those wires held together by devices referred to as a wire nuts or the like. With specific reference to a switch apparatus, for example, the neutral and ground wires of one cable would typically be electrically joined with the neutral and ground wires, respectively, of another cable and held together with wire nuts, whereas the hot wires would be connected to respective junctions of the switch so as to couple each hot wire to a respective pole of the switch.
Once the selected wires are connected to the junctions of the plug receptacle or switch apparatus, and the various wires joined together with wire nuts as before described, all of the wires, the wire nuts, and the housing of the plug receptacle or switch apparatus must be placed within the junction box. Thereafter, the plug receptacle or switch apparatus is usually secured to the junction box by a pair of screws which are threadably received in threaded lugs extending from the junction box walls. A cover plate may then be placed over the front of the plug receptacle or switch apparatus and secured thereto by one or more screws, as is conventional. The junction box is further necessary for safety to insure that someone or something does not accidentally come into contact with the otherwise exposed junctions on the plug receptacle or switch apparatus and/or any wire portion which may otherwise be left or become exposed.
All of these foregoing steps necessarily entail much time on the part of highly-paid electricians, thus making the labor costs associated with wiring a building structure very expensive. Similarly, material costs can become quite large due to the necessity of providing junction boxes in association with each plug receptacle and/or switch apparatus, as well as the various wire nuts and the like which are utilized to join certain of the wires together within the junction boxes. Further, with existing structures, it is often necessary to open up a large access area in the wall in order to install a new or additional junction box, such as where an outlet is to be added. Subsequently, the wall must be patched around the periphery of the new junction box. Such procedures can be very time consuming and costly and may discourage addition of further electrical plug receptacles or switches to existing structures.
Devices have been proposed to eliminate certain of the above-mentioned time-consuming steps, such as providing a plug receptacle and/or switch apparatus with insulation piercing structures by which individual wires of the sheath cable may be coupled to the device without the step of removing the insulation therefrom. Devices of this type are shown by way of example in U.S. Pat. Nos. 4,500,746; 4,379,605; 3,710,305; 3,163,482; 2,934,737; 2,952,004; and 2,873,435. Specifically, the terminal end of an insulated wire would be placed within the structure and the apparatus thereafter manipulated to cause a conductive knife or edge to pierce through the insulation and make electrical contact with the wire within. The conductive knife or edge is electrically coupled to a plug receptacle contact or switch pole within the housing of the apparatus whereby the wire is then electrically connected to the contact or pole. While this type of apparatus may save the time necessary for the electrician to strip the insulation from the wire, it does not save the time necessary for the electrician to cut away the sheathing nor does it eliminate the need for caution to avoid damage to the insulation and/or wires within the cable when removing the sheathing.
With the foregoing time-saving devices, it is still also necessary for the electrician to strip the insulation and join together the exposed terminal ends of those wires which must be separately joined together to form a complete circuit. Here, too, apparatus has previously been devised by which the terminal ends of wires may be coupled together without stripping the insulation, such as shown by way of example in U.S. Pat. Nos. 4,451,104 and 1,290,153. Such apparatus might eliminate one of the steps mentioned above, but suffer from the same drawbacks of not eliminating certain time-consuming steps such as removing the sheath, nor do they render unnecessary the precautions necessary as described above. Further, such apparatus still require the expenditure of material costs. That is, some separate apparatus is still required to join the wires together. In any event, applicants are not aware that such insulation piercing devices have been used in connection with the large gauge of wire in the sheathed cables commonly encountered in building structures. It is further a possibility that such devices have not been employed in wiring plug receptacle and/or switch apparatus because they may have to be much larger than currently-used wire nuts in order to accommodate the gauge of the wires involved. There is only limited space within the junction box to place all of the wires and related coupling structures, as well as the housing of the plug receptacle or switch apparatus. Hence, the possibility of requiring large size for the insulation piercing coupling devices would make them undesirable and, even if used, such devices would not eliminate the time expenditure necessary to actually join the wires.
Finally, it has been known to utilize insulation piercing techniques to couple each wire of a two wire cable to the respective conductors of an electrical lamp or the like, such as shown in U.S. Pat. No. 1,500,641. The cable shown therein comprises only a pair of wires which are surrounded by the same insulation. Further, the device of that patent is not disclosed to accommodate a cable wherein the wires are separately insulated. Moreover, it does not appear possible with that device to accommodate a three wire sheathed cable of the type which is commonly encountered in wiring utilized for building structures. Indeed, there is no provision in that device for electrically coupling to more than two wires.
The present invention, therefore, has as an object to provide an electrical apparatus which can be coupled to a sheathed cable having three or more wires therein without the necessity of removing the sheathing and/or insulation of the individual wires within the sheathing.
A further object of the present invention is to provide such an electrical apparatus in which one or more wires in one cable may be electrically coupled to one or more wires in another sheathed cable without the necessity of cutting either of the cables.
An even further object of the present invention is to provide such an electrical apparatus in which one or more wires of one cable may be coupled to one or more wires in another cable without the necessity of removing sheathing and/or insulation from either of the cables.
A yet further object of the present invention is to provide such an electrical apparatus in which selected wires of a cable may be electrically coupled to the appropriate contacts or poles of a plug receptacle or switch while simultaneously electrically coupling those selected wires to selected wires of another cable.
A still further object of the present invention is to provide such an electrical apparatus in which selected wires of a cable may be electrically coupled to the appropriate contacts or poles of a plug receptacle or switch while simultaneously electrically coupling those selected wires to selected wires of another cable without the necessity to remove the sheathing and/or insulation of the individual wires within the sheathing of either of the cables.
A still further object of the present invention is to provide such an electrical apparatus wherein the wires of the cables are inaccessible once the cable is coupled to the apparatus for safety purposes.
An even further object of the present invention is to provide such an electrical apparatus of the aforementioned type which can be mounted to a wall or the like of a building structure without the necessity to utilize junction boxes for the wiring or to hold the apparatus.
A yet further object of the present invention is to provide an electrical switch apparatus which can be coupled to respective and electrically isolated portions of a selected wire of a sheathed cable without the necessity for separately cutting the cable and/or wire and without the necessity of removing sheathing and/or insulation from the cable or wires thereof.
A further object of the present invention is to provide apparatus of the aforementioned type which is relatively simple and straightforward in use and has few moving parts associated therewith.